Brian Corcoran

ABSTRACT This paper focuses on the development and characterization of a waveguide-based photonic sensing platform for the detection of biofilm. This integrated photonic platform is based upon the high sensitivity of an optical field distribution formed in optical waveguides and the resulting changes in the refractive index and absorption of this environment.The sensor platform and materials formulations were established from simulation studies conducted with the Olympios software. These simulations demonstrated the importance of correctly specifying the material refractive index to achieve single-mode waveguides. They also highlighted the necessity to deposit a high refractive index layer (HRIL) on top of the optical waveguides in order to increase the intensity of the evanescent field responsible for the sensing performance of the platform.Platform fabrication exploited a low-cost process using photocurable organic–inorganic hybrid sol–gel materials, which were microstructured by UV-photolithography to form channel optical waveguides. A tantalum-based material was synthesized using the sol–gel process with refractive index as high as 1.87. This material was developed, optically characterized and applied as an evanescent field enhancement layer, deposited at the surface of the waveguide to increase the sensitivity of the sensing platform.The sensor characterization was performed by monitoring the output intensity of the optical waveguide while contaminated water was monitored in a quasi-static flow-rate (0.5 ml/s) on the platform. It is shown that our biosensor platform was able to detect the biofilm formation after 10 min of reactions, demonstrating the early stage biofilm formation in quasi-static flow-rate. Furthermore, the sensing performances of our photonic platform were found to be strongly dependent on the thickness of the HRIL, confirming the simulations studies.This work proved the concept of employing a waveguide-based photonic platform for the early detection of biofilm formation, including the induction phase, and as such, we believe this system has immense potential for future applications as a label-free and real-time biosensor platform.

... LED sensors are minimal and associated costs are kept very low due to the simplicity of design. ... The aim of this paper is to outline the development of both a WCSN based on novel LED gas sensors, and the environmental test chamber that was used for initial evaluation of the ...

ABSTRACT In the literature, several exergy analysis approaches have been proposed to investigate desalination processes. It is not clear, however, which approach is the most appropriate or indeed whether all approaches are valid. The objective of this paper is to review the various methods and to critically assess their assumptions, limitations, advantages and disadvantages. The main focus of this work is the chemical exergy term. Several exergy calculation models were examined and compared using a dataset from the literature. In addition, an accurate approach to calculate the chemical exergy of electrolyte solutions, based on the Pitzer equations, was proposed. The models assessed were: (1) the ideal mixture model (NaCl and water), (2) the ideal mixture model (seawater salt and water), (3) the Sharqawy seawater functions, and (4) the electrolyte solution model (Pitzer equations, NaCl and water), (5) the model used by Drioli et al. and (6) the dissociated ion approach (NaCl and water). Four of the six approaches produced very similar results. Moreover, one other exergy calculation method was found to have serious limitations. The findings presented here show that the choice of exergy model can have a significant impact on the results obtained and that considerable care must be taken to select the most suitable approach.

Exergy, the quality of energy, is not conserved but is destroyed due to process irreversibilities. This exergy destruction can be quantified using an exergy balance which “may be looked upon as a statement of the law of degradation of energy [1]”. Exergy analyses have been applied to the desalination industry, however, based on an extensive review of the desalination exergy literature, it is evident that several desalination exergy models exist, presenting a challenge to those wishing to undertake an exergy analysis. How does one know which model to use and whether these models give similar results? This paper investigates two exergy calculation models (Model A and Model B) in depth, and considers both models in light of the specific physical and chemical exergy definitions described in key exergy texts (Model C). Results showed that the maximum percentage difference in specific physical exergy at each process stage was 2.07% for Model A and Model B. However, the specific chemical e...

Support for transition from Leaving Certificate and entry to college for 1 st year engineering students can be difficult to achieve. This new course offers an innovative project based approach to learning for 1 st years with an introduction to design to build confidence in student ability and give motivation in research and discovery skills. The project takes place in small groups and relies heavily on presentation, group and individual skills. The Mechanical and Manufacturing and the Electronic Engineering Schools at Dublin City University offered this new module for all first year Engineering Students in 2006. The course entitled, 'Project and Laboratory Skills' was an immediate success with increased participation and retention rates and a high level of academic success in assessment. This paper highlights the overall module concepts, teaching and learning outcomes and the resources required for such a module.

We report a microfluidic chip-based hydrodynamic focusing approach that minimizes sample volume for the analysis of cell-surface interactions under controlled fluid-shear conditions. Assays of statistically meaningful numbers of translocating platelets interacting with immobilized von Willebrand factor at arterial shear rates (∼1500 s(-1)) are demonstrated. By controlling spatial disposition and relative flow rates of two contacting fluid streams, e.g., sample (blood) and aqueous buffer, on-chip hydrodynamic focusing guides the cell-containing stream across the protein surface as a thin fluid layer, consuming ∼50 μL of undiluted whole blood for a 2-min platelet assay. Control of wall shear stress is independent of sample consumption for a given flow time. The device design implements a mass-manufacturable fabrication approach. Fluorescent labeling of cells enables readout using standard microscopy tools. Customized image-analysis software rapidly quantifies cellular surface coverage and aggregate size distributions as a function of time during blood-flow analyses, facilitating assessment of drug treatment efficacy or diagnosis of disease state.

Exergy analysis has been applied to desalination membrane processes in an effort to characterise energy consumption and to optimise energy efficiency. Several models have been used to this end in the literature. One assumption that is common in these analyses is that of ideal solution behavior. However, seawater and other aqueous solutions of interest do not behave ideally. Indeed, even when ideal behavior is not assumed, there are several approaches to calculate these activity values, which are typically a function of the molality and ionic strength of the electrolytic solution. What is not clear from the published literature is the impact that the choice of activity calculation model has on the exergy analysis results. The objective of this research was to undertake the exergy analysis of a seawater membrane desalination plant using the Szargut chemical exergy approach and to compare the activity calculation approaches. The chemical exergy of the seawater was calculated using seve...